Duke University Medical Center and the University of North Carolina at Chapel Hill Medical Center (UNC-CH) will form a Clinical Center in the Pediatric Heart Disease Clinical Research Network. Duke will be the primary site and UNC-CH the subsite. The likely success of this proposed collaboration is supported by the previous and ongoing joint participation by the Centers at multiple levels and over many years. These interactions include collaborations in patient care, post-graduate education, and federally funded clinical research in which Duke and UNC-CH have both been primary and subsites. The longstanding research programs at the centers have studied a broad range of issues relevant to pediatric heart disease, including the pathophysiologic basis of the post-cardiopulmonary bypass (CPB) syndrome, dysrhythmias, and altered ventricular function in patients with congenital cardiac defects and heart failure. The studies have ranged from the contractile proteins to the in vivo heart of the patient and have examined the treatment of dysrhythmias, catheter-based device implantation, and testing the efficacy and safety of pharmacologic drugs. Annually our combined programs have over 11,000 outpatient visits and perform in excess of 600 cardiac catheterizations, 8,000 echocardiograms, 200 electrophysiological interventions/ablations, 150 catheter-based interventions, and 490 pediatric cardiac surgical procedures. The proposed double blind randomized controlled trials are: a long-term study of three years duration, carvedilol efficacy and safety in the Fontan patient with depressed ventricular function; a short-term study of two years duration, the efficacy and safety of methylprednisolone in preventing the post-CPB syndrome in the infant. The primary objective of the carvedilol trial is the Clinical Global Assessment by the physician. In the adult with heart failure, greater sympathetic nervous system activation is associated with worse clinical course. Carvedilol has been found to improve quality of life and decrease mortality in these patients. Our trial will test the hypothesis that carvedilol improves quality of life, clinical course, and ejection fraction in the Fontan patient. Methylprednisolone is widely used and thought to be efficacious in decreasing the morbidity of the post-CPB syndrome. We will test the hypothesis that methylprednisolone decreases PICU stay, maintains normal vascular permeability, prevents renal and hepatic damage, and improves the clinical course. We look forward to participating in the Network and improving the care of infants and children with congenital and acquired heart disease.